Consider pairing a large vase with a few, simple large flowers. Look for varieties with thicker stems such as sunflowers. Remove any leaves or thorns on the stem for a clean look under the water. Flowers with large heads, such as sunflowers, will elegantly fill the space and work with the size of the vase. Avoid adding diminutive flowers or greenery as accents; they will draw attention away from the simplicity of size as a design feature in the arrangement.
Filling a large vase with voluminous flowers balances the size of the vase. Consider using hydrangeas and hyacinth. Let the flowers fall naturally, as flowers with heavier heads will droop faster, for a dramatic effect.
Use pebbles at the bottom of the vase to stabilize stems. Bind a handful of flowers with twine or ribbon at the top half of the arrangement and lean the flowers to one side in the vase. This should leave half the opening of the vase exposed and draw attention to the details in the vase. Rather than using smaller flowers to fill the space, purposely leaving part of the vase exposed and angling the flowers adds an asymmetrical design feature to the arrangement.